I love Twilicorn. *Equestria Girls 1* set a high keynote for Season 4 -- and for what Twilight would be like as a Princess. I love how Starlight has developed as a character.
I feel that Derpy/Muffins needed to be presented with more dignity, to avoid making fun of handicapped people. (I feel that Snips and Snails started off as ugly caricatures of boys.) To be fair, the Button Mash videos looked deceptively like official material -- and there was some language that Hasbro would have never allowed in the show, I think. On that note, *Fighting Is Magic* could have easily misrepresented the show, especially since it looked too much like something that could have been licensed.
I guess Snowdrop got a pass because Hasbro couldn't say no to a blind filly who could see with her heart. Bottom line -- you have to know how to make friends with the right people. You have to know the values of the people in charge, so that you don't make a false step.